Entries in the real Route Discovery table only exist during the route discovery time. "LQI and RSSI from every node" makes no sense. They only apply to devices in a direct link range. If ED is multiple hops away from some device, then they will not apply to the ED.
So you need to clarify what you actually want to get. In any event, those parameters can only be determined if devices send frames, so make all devices send frames to your target device. Each NWK_DataInd_t will have those parameters, so you can collect them in the application.